This happens infrequently and I believe I recall this from the pre-jogamp version 1.5.2 and earlier:

Error destroying java3d component
java.lang.NullPointerException
at javax.media.j3d.NodeRetained.clearLive(NodeRetained.java:737)
at javax.media.j3d.GroupRetained.clearLive(GroupRetained.java:2686)
at javax.media.j3d.GroupRetained.clearLive(GroupRetained.java:2733)
at javax.media.j3d.Locale.doRemoveBranchGraph(Locale.java:344)
at javax.media.j3d.Locale.removeFromUniverse(Locale.java:313)
at javax.media.j3d.VirtualUniverse.removeAllLocales(VirtualUniverse.java:358)

I'm using 1.6.0pre9

Of course, It's always easier growing a graph than paring it back. I'm trying to plug memory leaks using Java3d

Any help appreciated, thank you to the developers and community contributors for keeping this alive.